Question

On our developer machines, we have Silverlight 4 installed. We upgraded to VS 2010 SP1, and now our Silverlight projects won’t open; it is prompting us that we need to install the newer version of Silverlight, and takes us to a link to download Silverlight 5.

We are not ready to go to Silverlight 5 yet, and need to be able to open up our Silverlight 4 projects in VS 2010 SP1.

Any suggestions?

Answer 1

This sounds like it may be a duplicate of this question, but since you say you had Silverlight 4 installed before it may not be.

I recently rebuild my development machine and ran into a similar problem, but closer to that other question. Ultimately, I found this blog post, which led me to a installer for Silverlight 4 Developer Runtime.

There was one issue the author mentioned, that I have not run into yet:

I have noticed a large number of people hitting this page. Well,
let me help you guys out a little more. It turns out that EVERY time
Microsoft decides to update the Silverlight runtime. A patch, string
change, someone looked at it wrong, the Developer runtime gets
invalidated.

You will need to reinstall it each time. So make sure you keep it
handy! Thanks Microsoft for such a wonder feature. I love reinstalling
things every week.

EDIT:

I ran into the issue mentioned above and reinstalling the Silverlight 4 Developer Runtime did not fix the issue for me. I ended up installing the Silverlight 5 Developer Runtime (32 bit, 64 bit), which I obtained from this page, and that fixed the issue.